1. Field of the Invention
The present invention relates to an apparatus for arranging short cylindrical bodies in general, and relates in particular to its application to a drying apparatus capable of changing the direction of transport of a plurality of pellets, and an associated inspection apparatus for inspecting the external surface quality of each pellet.
2. Technical Background of the Invention
In general, the pellets which are charged into nuclear fuel rods are made by pressing a fuel powder, such as uranium dioxide, into cylindrical pellets of a short rod shape, and sintering the pressed pellets. In the process of producing such pellets, surface chips and other surface defects are sometimes produced on the external surfaces of the pellets. It is therefore necessary to inspect the surface quality of the pellets for the presence of surface defects. Conventionally, such inspections have been performed visually on every sintered pellet to eliminate defective pellets so as to assure the reliability of the reactor operation.
However, such a manual inspection method is not only labor-intensive and time-consuming but also places a large mental stresses on the inspectors who carry out such tasks on a daily basis. To alleviate such problems, the present inventors have previously presented an inspection apparatus for inspecting the surface quality of the pellets based on image processing technology (U.S. Pat. No. 5,019,326).
The inspection apparatus is usually associated with a wet grinding device. The pellets subjected to wet grinding are discharged continuously from the wet grinder with the axis of the short rod-shaped pellets aligned in the transport direction. To inspect the surface quality of the pellets efficiently, it is necessary to quickly change the direction of movement of the pellet from its axial direction to its radial direction in the inspection apparatus so that both the end surfaces and the side surface of the short rod-shaped pellets can be inspected.
Also, for pellet handling purposes, the planar end surfaces of the pellets are provided with a pair of depressions (dish sections), which are prone to collecting moisture from the wet grinding operation. The moisture sometimes affects optical recording of the surface images, because of false surface signals from abnormal reflections and refractions caused by droplets of water collecting in the dish sections.
The presence of water thus interferes with the proper optical inspection of the wet ground pellets, and it is necessary that the pellets be dried completely before optical inspection.